High-silica rhyolites in the terminal stage of massive Cretaceous volcanism, SE China: Modified crustal sources and low-pressure magma chamber

Abstract Late Cretaceous felsic volcanism erupted as calderas in the terminal stage of the massive Cretaceous volcanism in SE China. This paper reports comprehensive geochemical and isotopic data for high-silica rhyolites from the Shiniushan and Xiaoxiong calderas in eastern Fujian–Zhejiang provinces, SE China. Zircon U Pb dating constrains these rhyolites eruptions to 94–92 Ma and 93–89 Ma in the sites of the two calderas. All the samples possess high-silica contents with peraluminous characteristics and are enriched in light rare earth elements (LREEs), Rb, and Th U and depleted in Ba, Nb Ta, Sr and Eu. These samples have high whole-rock F (114–596 ppm) but low Cl (3.3–54.8 ppm) contents. Apatite minerals separated from the high-silica rhyolites are classified as fluorapatite and show F-rich (F > 3.56 wt%), Cl-poor (Cl